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cup vrs. psi

Discussion in 'Ammunition & Reloading' started by prkrgrp, Dec 19, 2013.

  1. prkrgrp

    prkrgrp oregon Active Member

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    ok I'm trying to load up some new rounds with imr8208 xbr.
    the load chart shows cup and psi from what i can tell there is some difference.

    do I dare :laugh:
     
  2. alphapygmy

    alphapygmy Yamhill County Active Member

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  3. AMProducts

    AMProducts Maple Valley, WA Jerk, Ammo Manufacturer Silver Supporter

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    Sweet Jesus! you just asked one of the most complex questions in internal ballistics. The above link does a pretty good job of explaining the differences, and in general I consider the two to be correlated, but unrelated. CUP, LUP (lead units of pressure) and PSI really don't translate in a reasonable fashion to one another. I am inclined to say if you have pressure data for the cartridge in CUP and PSI, and powder data in PSI stick with that. I generally use PSI because I don't have a copper crusher, but I do have a ballistic transducer, which gives me measurement in PSI. Everything else kinda gives me a headache.
     
    skeezix, jbett98, orygun and 3 others like this.
  4. prkrgrp

    prkrgrp oregon Active Member

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    hahahaha I try to read as much as I can before posting, the more research I did the more confused I got. and I pretty much came to the same conclusion.
    thanks
     
  5. Lindy

    Lindy Central Ca. Member

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    That gives Me a headache !

    Good Shooting

    Lindy
     
  6. Jamie6.5

    Jamie6.5 Western OR Well-Known Member

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    Throw in CIP specs vs SAAMI specs and you are well on your way to a migraine!

    Here's a handy online chart:
    Cartridge Pressure Standards